Adhesive composition comprising water, bentonite and polyvinyl methyl ether



Patented Apr. 28, 1959 United States Patent ()fiice ADHESIVE COMPOSITION COMPRISING WATER, BENTONITE AND POLYVINYL METHYL ETHER Anthony J. Allegretti, Westchester, Ill., assignor, by mesne assignments, to R. R. Donnelley & Sons Company,

Chicago, 111., a corporation of Delaware No Drawing. Application June 13, 1955 Serial No. 515,225

2 Claims. (Cl. 26029.6)

This invention relates to an adhesive composition particularly suitable for applying paper labels to hard inked surfaces such as are encountered in high quality magazines and the like.

In devising a suitable adhesive composition for adhering paper labels or the like to the inked surfaces of magazines and similar periodicals, it is diflicult to compound a completely suitable composition because of the many problems encountered. Thus, the magazine pages, and particularly the covers, are hard and glossy and are covered with ink which is ordinarily a hard heat-set ink. It is difliicult to adhere to this surface. In fact, the problem has been so great that some national publications actually leave a bare uninked rectangle on one cover for applying the label to this uninked surface.

The labels are ordinarily applied by means of a mailing machine. A popular type of mailing machine uses a rotating applicator with four arms, each carrying a transfer surface of metal for transferring adhesive from a container to the cover, after which the label is pressed onto the area coated by the adhesive. This applicator in this common type of mailer rotates at about 4500 rpm. so that labels are applied to between 20,000 and 27,000 magazines per hour. Because of this high speed, ordinary adhesive compositions are either thrown from the rotating applicator by the centrifugal force or the adhesive composition formerly used often causes stringing or necking of the adhesive without a sharp break. Furthermore, it has been quite difiicult to have enough adhesive force in the adhesive composition to cause it to cling to the transfer members and also to have a sufficient amount of cohesive force to prevent this stringing or necking.

Another problem in devising a suitable adhesive composition for this use is that many adhesives which are satisfactory in every other respect do not have sufficient agitation stability so that when the composition is agitated it tends to break down. This has been particularly true of the emulsion-type compositions.

A major problem in prior art adhesive compositions is the difficulty of removing it from the paper when the magazine eventually becomes scrap. As is well known, scrap paper is graded and priced according to certain standards. Thus, paper which contains considerable amounts of foreign material can only be sold at a relatively low price. In reclaiming the scrap paper, aqueous alkali solutions are used to remove the ink. As many of the prior adhesives are not dispersible or soluble in these solutions, adhesive agglomerates are formed and the scrap paper is ruined for high grade uses. Thus, these agglomerates become deposited in the de-inking operations as small particles on the reclaimed paper pulp sheets. These small particles of adhesive are not only unsightly but cause contacting sheets to adhere together. Furthermore, these adhesive particles or agglomerates tend to clog the felting screens of the paper machines so as to prevent proper felting of the pulp.

Another ditficulty with these adhesive agglomerates is that they become deposited on the heated drying rolls where their adhesiveness is sufiiciently great to cause tearing of the paper sheet passing over these rolls.

The adhesive composition of this invention successfully solves all of these problems. Thus, the composition is such that mailing machines can be operated at extremely high speed without difficulty and the adhesive clings tenaciously to the inked surface so as to hold the address label securely. Apparently, the adhesive of this composition has a partial solvent action on the ink'beneath the label so as to bind the label securely to the surface. Furthermore, the adhesive of this composition is soluble or at least dispersible in the alkaline aqueous de-inking solution so that the adhesive passes ofi? with the solution during the reclaiming of waste paper containing the adhesive.

One of the objects of this invention is to provide an adhesive composition for applying paper labels to inked surfaces comprising about 1-5 parts of bentonite, about 72-220 parts of water, and about 2244 parts of a polymer which may be a copolymer of vinyl acetate and crotonic acid, a copolymer of vinyl acetate and acrylic acid, a copolymer of vinyl acetate and maleic acid, or polyvinyl methyl ether.

Other objects and advantages of the invention will be apparent from the following detailed description of the invention taken in conjunction with the accompanying claims.

The composition of this invention comprises about 1-5 parts by weight of bentonite and preferably about 2-4V2 parts, about 72-220 parts of water and preferably about 72-92 parts, and about 2244 parts of a polymer and preferably about 22-27 parts.

This polymer may be a copolymer of vinyl acetate and crotonic acid, a copolymer of vinyl acetate and acrylic acid, a copolymer of vinyl acetate and maleic acid, or polyvinyl methyl ether.

The above copolymer of vinyl acetate and crotonic acid, acrylic acid, or maleic acid preferably contains about -98 parts by weight of vinyl acetate and 10-2 parts by Weight of the acid. The polyvinyl methyl ether that may be used is preferably one giving a specific viscosity reading of about 0.5-0.9 when a one gram portion of the ether dissolved in milliliters of benzene is measured at 25 C.

The polymer is preferably used either dispersed or dissolved in water. Thus, when the polymer that is employed is polyvinyl methyl ether, it may be conveniently used in a water solution such as a 50 percent by weight solution in water. When any of the polymers is so employed, the water to make up the polymer solution or dispersion is taken from the total amount of Water set out in the above formulas.

Similarly, when the polymer is a copolymer of vinyl acetate and crotonic acid, acrylic acid, or maleic acid, the copolymer is preferably employed in an emulsion of the copolymer in water, with an emulsion containing 50 percent Water and 50 percent copolymer being suitable for this purpose.

One example of preparing an adhesive composition of the type disclosed and claimed herein is to mix thoroughly two parts by weight of bentonite with about 50 parts by weight of water. This mixture was continuously agitated until the particles of bentonite which were sufiiciently small to pass through a 200 mesh standard screen were completely suspended and swollen. This took about 20-30 minutes of continuous agitation with a standard propeller type stirrer. As soon as the slurry was uniform and substantially all of the bentonite had been suspended and had swollen to its maximum amount, 44 parts of a 50 percent solution of polyvinyl methyl ether in water were added and the entire mixture mixed thoroughly to a uniform consistency. At the completion of this mixing, the composition was ready for use. The polyvinyl methyl ether that was employed had a specific viscosity within the range of 0.5-0.9 as indicated by measuring the viscosity of a one gram. solution of the ether in 100v milliliters of benzene at 25 C.

Having described my invention as related to the embodirnents set out herein, it is my intention that the invention be not limited by any of the details of description unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

I claim:

1. An adhesive composition for applying paper labels to inked surfaces, comprising: about 1-5 parts of hen- 4 tonite; about 72220 parts of water; and about 22-44 parts of polyvinyl methyl ether, all said parts being by weight. 7 i

2. The composition of claim 1 wherein said polyvinyl methyl ether has a specific viscosity of about 0.5-0.9 as determined when 1 gram of said ether is dissolved in 100 milliliters of benzene at 25 C.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN ADHESIVE COMPOSITION FOR APPLYING PAPER LABELS TO INKED SURFACES, COMPRISING: ABOUT 1-5 PARTS OF BENTONITE; ABOUT 72-220 PARTS OF WATER AND ABOUT 22-44 PARTS OF POLYVINYL METHYL ETHER, ALL SAID PARTS BEING BY WEIGHT. 